This invention relates to a method and apparatus for terminating one end of a cable and, in particular, to a high strength device for terminating the distal end of a cable used for articulating the viewing head of an endoscopic or borescopic insertion tube.
Most endoscopes and borescopes are provided with an insertion tube having a bendable steering section which allows the viewing head mounted at the distal end of the tube to be guided along what sometimes might be a tortuous path of travel. Typically, the bendable steering section is mounted immediately behind the viewing head of the instrument and is articulated by means of a plurality of control cables. A steering section of this nature is disclosed in U.S. Pat. No. 4,796,607.
The proximal ends of the cables are connected by pulleys or gear racks to control knobs on the handle of the insertion tube and are passed through the steering section and an end plate located at the distal end of the steering section. The end plate is secured to the viewing head of the instrument. The distal end of each cable is terminated by slipping brass or stainless steel cylinders thereover and the cylinder is soldered to the cable. During articulation the terminated end of the cables are pulled with some force against the end plate.
The brass or stainless steel cylinder termination devices have certain advantages that make them attractive for use in endoscopic applications. They are well suited for terminating small diameter cables and the joint between the cable and the termination cylinder is easily formed. The solder used in the joint penetrates the wire strands of the cable to strengthen the joint and to prevent the wire strands from unwrapping in the event the termination device fails. Unraveled strands can harm adjacent parts of the instrument or find their way into the target region that is undergoing inspection.